TITRATION OF TETANUS ANTITOXIN BY PASSIVE HEMAGGLUTINATION II. SEROLOGICAL CHARACTERISTICS OF ANTITOXIN PRODUCTION IN RABBITS AND MONKEYS

Abstract
Production of tetanus antitoxin in rabbits and monkeys was followed by passive hemagglutination (HA) and toxin-neutralization (TN) tests. The HA activity was observed in Ig[immunoglobulin]M and IgG in both animals. In rabbits, IgM antitoxin was detected as early as 7 days, reached the maximum titer in 10-14 days and disappeared in 3 wk after the primary immunization. Antitoxin of IgG class was detected in 10 days, and increased gradually. The ratio of HA/TN titers (serum ratio) was high at an early stage of primary immunization and approached unity in 3-4 wk. Unlike the case of guinea pigs, IgM contributed greatly to this high ratio. Most rabbits produced IgG antitoxin of high ratios at early stages of immunization. The immune response of monkeys showed a pattern very similar to that of rabbits except a few days'' delay in the time course of antitoxin titers. No IgG antitoxin with a high serum ratio was demonstrated. Therefore, the high serum ratio of early sera could be accounted for mainly by IgM. In response to secondary immunization, no IgM antitoxin was detected in either animal. No definite correlation between serum ratio and avidity in terms of dilution ratio was demonstrated. However, the dilution ratio and serum ratio were high at an early stage of immunization and gradually decreased, though the magnitudes of the ratios were variable depending on individual animals.